1. Field of the Invention
The present invention relates to a control method for a premixed compression ignition internal combustion engine in which a gaseous mixture of an oxygen-containing gas and a fuel is compressed and self-ignited within a cylinder.
2. Description of the Related Art
A premixed compression ignition internal combustion engine, in which a gaseous mixture of an oxygen-containing gas such as air and a fuel such as gasoline is compressed and self-ignited within a cylinder, can burn a homogeneous gaseous mixture, and moreover can burn even a very lean gaseous mixture. As a result, the premixed compression ignition internal combustion engine is getting attention as an internal combustion engine that can achieve high fuel efficiency and also can reduce hazardous substances in exhaust gas.
However, the premixed compression ignition internal combustion engine has a problem in that it is difficult to arbitrarily control the ignition timing, which results in abnormal combustion such as knocking because the gaseous mixture is self-ignited. The reason for this is that the self-ignition of the gaseous mixture is dominated by the chemical reactivity inherent in the fuel and hysteresis in pressure and temperature produced by the compression of the gaseous mixture.
Conventionally, there has been known a control method in which the temperature of intake air is changed or exhaust gas after combustion is recirculated to intake air in order to adjust the ignition timing.
However, the conventional control method has a disadvantage that it is difficult to respond to a sudden change in operating conditions of the internal combustion engine.